1. Field of the Invention
The present invention relates to an automatic, self-energizing brake and more particularly, to an automatic, self-energizing brake which may be used with a motor, such as an electric motor.
2. Description of the Related Art
A motor driven device often needs a braking mechanism to prevent the movement thereof when the motor is no longer applying torque to the device. For example, an automobile has a parking brake to prevent it from moving when the motor is turned off.
A motor driven device which is driven by an electric motor may also need a braking mechanism to prevent the movement of the device when the motor is de-energized. Unfortunately, such braking mechanisms have tended to be either manual mechanisms which must be operated by a user or automatic mechanisms which have tended to be complicated, expensive, and failure-prone.
U.S. Pat. No. 6,376,948 to Li-Yang discloses a motor-synchronous exciting brake which utilizes the magnetic field generated by the electric motor to disengage a braking mechanism. When current to the electric motor is cut off, the magnetic field generated by the electric motor disappears and the braking mechanism is engaged to prevent the motor shaft from moving. The disclosed braking mechanism, however, is very complicated and must be disposed within the electric motor so as to make use of the magnetic field thereof.
U.S. Pat. No. 5,982,063 to Lutz et al. discloses another electric motor arrangement having an internal braking mechanism. While the disclosed mechanism is simpler than that of Li-Yang noted above, the braking mechanism of Lutz et al. requires the energization of an electromagnet to engage the braking mechanism, thereby requiring either a manual operation or requiring additional circuitry for the braking mechanism.
U.S. Pat. No. 5,932,944 to Ko discloses still another electric motor assembly with a braking mechanism. While the mechanism of this patent does not require the electromagnet of Lutz et al., nor is it internal to the electric motor as in both Li-Yang and Lutz et al., the braking mechanism of Ko is complicated and is integral with a complicated gearbox assembly.
An aspect of the present invention is to provide an automatic self-energizing brake which may be used with a motor, such as an electric motor.
In an aspect of the present invention, a moving brake section, including a brake friction material located on a portion of a face thereof perpendicular to its axis of rotation is automatically urged toward a brake mating surface upon the motor coming to a stop, thereby automatically energizing the brake, and is automatically urged away from the brake mating surface upon the motor beginning its rotation, thereby automatically de-energizing the brake.
In another aspect of the present invention, a bearing carrier having at least two bearings is arranged to interact with a trough of the moving brake section to urge the moving brake section away from the brake mating surface.
In still another aspect of the present invention, an elastic means, such as a spring, is used to urge the brake moving section toward the brake mating surface.
These and other objects of the present invention may be achieved by providing a self-energizing brake for a motor, the self-energizing brake comprising: a bearing carrier arranged to be mechanically connected to a shaft of the motor; a moving brake section located coaxially with said bearing carrier, said moving brake section including a brake friction material located on a portion of a face thereof perpendicular to said axis of rotation of said bearing carrier; an output torque transmitting means mechanically connected to said moving brake section; a brake mating surface located on said motor and perpendicular to said axis of rotation of said bearing carrier, said brake mating surface initially mating with said brake friction material so as to be in contact therewith upon said shaft of the motor being at rest; an elastic means urging said moving brake section in an axial direction toward said brake mating surface; wherein upon said shaft of said motor rotating, said bearing carrier causes said moving brake section and said brake friction material to move axially away from said brake mating surface, resulting in said brake friction material being spaced apart from said brake mating surface; and wherein upon said shaft of said motor further rotating, said bearing carrier causes a cessation of said axial movement of said moving brake section and said brake friction material; and wherein upon said shaft of said motor ceasing to rotate, said elastic means urging said moving brake section and said brake friction material to move axially toward said brake mating surface until said brake friction material is in contact therewith.
The foregoing and other objects of the present invention may also be achieved by providing a self-energized brake for a motor, the self-energizing brake comprising: a bearing carrier arranged to be mechanically connected to a shaft of the motor, said bearing carrier including at least two bearings, each bearing having an axis of rotation perpendicular to an axis of rotation of said bearing carrier; a moving brake section located coaxially with said bearing carrier, said moving brake section including a trough having at least two trough portions to respectively contain said at least two bearings, said trough portions each including a bearing ramp and a bearing stop for its respective bearing, and said moving brake section further including a brake friction material located on a portion of a face thereof perpendicular to said axis of rotation of said bearing carrier; an output torque transmitting means mechanically connected to said moving brake section; a brake mating surface located on said motor and perpendicular to said axis of rotation of said bearing carrier, said brake mating surface initially mating with said brake friction material so as to be in contact therewith upon said shaft of the motor being at rest; an elastic means and an elastic means retainer and an elastic means retainer fixing means, said elastic means and said elastic means retainer being located coaxially with said bearing carrier, said elastic means retainer fixing means preventing movement of said elastic means retainer in one axial direction and said elastic means urging said moving brake section in an axial direction toward said brake mating surface; and wherein upon said shaft of said motor rotating, said bearing carrier and said at least two bearings rotate until said bearings come in contact with and move up their respective bearing ramps, so as to cause said moving brake section and said brake friction material to move axially away from said brake mating surface, resulting in said brake friction material being spaced apart from said brake mating surface; and wherein upon said shaft of said motor further rotating, said bearing carrier and said at least two bearings further rotating until said bearings come up against their respective bearing stops, resulting in a cessation of said axial movement of said moving brake section and said brake friction material; and wherein upon said shaft of said motor ceasing to rotate, said elastic means urging said moving brake section and said brake friction material to move axially toward said brake mating surface, causing said at least two bearings to move away from their respective bearing stops and to roll down their respective bearing ramps until said brake friction material is again in contact with said brake mating surface.
In the present invention, the output torque transmitting means may include one of a gear or a pulley or sprocket and the elastic means may include a spring and the brake mating surface may include either a face of the motor or a plate located adjacent the motor.
In the present invention, the bearings may include one of a ball bearing or a roller bearing or a bushing and the elastic means retainer may include a washer shaped spring retainer and the elastic means retainer fixing means may include one of a retaining ring or a pin.
In the present invention, the bearing carrier may be mechanically connected to the shaft of the motor by one of set screws, a splined shaft, or a key and a matching keyway.
Lastly, in the present invention, each of the trough portions may have a major axis extending radially in a direction which is perpendicular to the axis of rotation of the bearing carrier and a width of each of the trough portions may increase in a direction away from the axis of rotation of the bearing carrier.
The foregoing and a better understanding of the present invention will become apparent from the following detailed description of an example embodiment and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the foregoing and following written and illustrated disclosure focuses on disclosing an example embodiment of the Invention, it should be clearly understood that the same is by way of illustration and example only and that the invention is not limited thereto. The spirit and scope of the present invention are limited only by the terms of the appended claims.